1. Field of the Invention
The present invention relates to a thin-film magnetic head and to a floating-type magnetic head provided with the thin-film magnetic head.
2. Description of the Related Art
As magnetoresistive-type thin-film magnetic heads, magnetoresistive (MR) heads provided with elements exhibiting a magnetoresistive effect, and giant magnetoresistive (GMR) heads provided with elements exhibiting a giant magnetoresistive effect, are known.
In the GMR head, the element exhibiting the giant magnetoresistive effect has a multilayered structure. There are several types of multilayered structure for producing the giant magnetoresistive effect. One example thereof is a spin-valve thin-film magnetic element provided with at least a free magnetic layer, a pinned magnetic layer, and a nonmagnetic layer, in which the structure is relatively simple, and the resistance variation ratio in an external magnetic field is increased. Examples of spin-valve thin-film magnetic elements are a single spin-valve thin-film magnetic element and a dual spin-valve thin-film magnetic element.
In order to align the magnetization direction of the free magnetic layer, a hard bias method or an exchange bias method is used. Recently, as the magnetic recording density is increased, the exchange bias method which is suitable for track narrowing is predominantly used.
FIG. 17 shows a thin-film magnetic head 501 provided with a conventional single spin-valve thin-film magnetic element 502 using the exchange bias method.
The thin-film magnetic head 501 is a read-only head, in which a pair of shielding layers 507 and 508 is deposited on both sides in the thickness direction of the spin-valve thin-film magnetic element 502 with insulating layers 505 and 506 therebetween, respectively.
Additionally, in FIG. 17, the Z direction corresponds to the traveling direction of a magnetic recording medium, the Y direction corresponds to the direction of a fringing magnetic field from the magnetic recording medium, and the X1 direction is the track width direction of the thin-film magnetic head 501.
The spin-valve thin-film magnetic element 502 is a so-called xe2x80x9cbottom-typexe2x80x9d single spin-valve thin-film magnetic element, in which one each of an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic conductive layer, and a free magnetic layer are deposited in that order.
In the spin-valve thin-film magnetic element 502, the insulating layer 506 composed of Al2O3 or the like is deposited on the lower shielding layer 508, and an antiferromagnetic layer 512, a pinned magnetic layer 513, a nonmagnetic conductive layer 514 composed of Cu or the like, and a free magnetic layer 515 are deposited on the insulating layer 506 in that order.
A pair of bias layers 516 is deposited on the free magnetic layer 515 with a separation therebetween in the X1 direction.
A pair of conductive layers 517 composed of Cu or the like is further deposited on the bias layers 516, and the insulating layer 505 composed of Al2O3 or the like is deposited over the conductive layers 517 and the free magnetic layer 515.
The upper shielding layer 507 is deposited on the insulating layer 505.
The antiferromagnetic layer 512 is composed of an antiferromagnetic material, such as a PtMn alloy, and an exchange coupling magnetic field (exchange anisotropic magnetic field) is produced at the interface between the pinned magnetic layer 513 and the antiferromagnetic layer 512, thus pinning the magnetization direction of the pinned magnetic layer 513 in the Y direction.
The bias layers 516 are composed of an antiferromagnetic material, such as an IrMn alloy, and an exchange coupling magnetic field (exchange anisotropic magnetic field) is produced at the interface between the bias layers 516 and the free magnetic layer 515. The exchange coupling magnetic field aligns the magnetization direction of the free magnetic layer 515 in the X1 direction, i.e., the free magnetic layer 515 is aligned in a single-domain state, thus suppressing Barkhausen noise.
Accordingly, the magnetization direction of the free magnetic layer 515 and the magnetization direction of the pinned magnetic layer 513 are orthogonal to each other.
Since the pair of bias layers 516 are formed with a separation therebetween, a portion of the free magnetic layer 515 is not covered by the bias layer 516, and this portion corresponds to a track section G2 of the thin-film magnetic head 501.
In the thin-film magnetic head 501, the magnetization direction of the free magnetic layer 515, which is aligned in the X1 direction, is changed due to a fringing magnetic field from a recording medium, such as a hard disk, and the electrical resistance of the spin-valve thin-film magnetic element 502 is changed because of the relationship between the magnetization direction of the free magnetic layer 515 and the magnetization direction of the pinned magnetic layer 513, which is pinned in the Y direction, and thus the fringing magnetic field from the magnetic medium is detected by a change in voltage due to the change in the electrical resistance.
However, in the conventional thin-film magnetic head 501, since the conductive layers 517 for applying a sensing current to the free magnetic layer 515 are deposited on the pair of bias layers 516, the sensing current flows in the bias layers 516. Since the bias layers 516, which are composed of the antiferromagnetic material, such as an IrMn alloy, have a high resistivity, when the sensing current flows in the bias layers 516, the temperature of the spin-valve thin-film magnetic element 502 may be increased.
If the temperature of the spin-valve thin-film magnetic element 502 is increased, the magnetization of the free magnetic layer 515 which is aligned by the bias layers 516 becomes disordered, resulting in an increase in Barkhausen noise.
Since the sensing current flows in the high-resistivity bias layers 516, the resistance of the spin-valve thin-film magnetic element 502 itself is increased, resulting in a decrease in reading output of the thin-film magnetic head 501.
Accordingly, it is an object of the present invention to provide a thin-film magnetic head, in which Barkhausen noise is decreased and reading output is increased by preventing a rise in the temperature of a spin-valve thin-film magnetic element, and it is another object of the present invention to provide a floating-type magnetic head provided with the thin-film magnetic head.
In one aspect, a thin-film magnetic head, in accordance with the present invention, includes a spin-valve thin-film magnetic element, and includes a first insulating layer and a second insulating layer each deposited on a side in the thickness direction of the spin-valve thin-film magnetic element, and a first shielding layer and a second shielding layer in contact with the first insulating layer and the second insulating layer, respectively. The spin-valve thin-film magnetic element includes a free magnetic layer, a nonmagnetic conductive layer in contact with the free magnetic layer, the nonmagnetic conductive layer being located on one side in the thickness direction of the free magnetic layer, a pinned magnetic layer in contact with the nonmagnetic conductive layer, an antiferromagnetic layer in contact with the pinned magnetic layer, the antiferromagnetic layer pinning the magnetization direction of the pinned magnetic layer, a pair of bias layers for aligning the magnetization direction of the free magnetic layer, and a pair of conductive layers for applying a sensing current to the free magnetic layer. The pair of conductive layers is located on one side in the thickness direction of the free magnetic layer. The pair of bias layers is located on the other side in the thickness direction of the free magnetic layer, is disposed on both sides in the track width direction of at least a portion of the second insulating layer, and is in contact with the free magnetic layer.
In another aspect, a thin-film magnetic head, in accordance with the present invention, includes a spin-valve thin-film magnetic element, and includes a first insulating layer and a second insulating layer each deposited on a side in the thickness direction of the spin-valve thin-film magnetic element, and a first shielding layer and a second shielding layer in contact with the first insulating layer and the second insulating layer, respectively. The spin-valve thin-film magnetic element includes a free magnetic layer; a first nonmagnetic conductive layer, a first pinned magnetic layer, and a first antiferromagnetic layer deposited on one side in the thickness direction of the free magnetic layer; a second nonmagnetic conductive layer, a second pinned magnetic layer, and a second antiferromagnetic layer deposited on the other side in the thickness direction of the free magnetic layer; a pair of conductive layers for applying a sensing current to the free magnetic layer; and a pair of bias layers in contact with the free magnetic layer, the pair of bias layers aligning the magnetization direction of the free magnetic layer. The pair of conductive layers is located on one side in the thickness direction of the free magnetic layer. The pair of bias layers is located on the other side in the thickness direction of the free magnetic layer, is disposed on both sides in the track width direction of at least a portion of the second insulating layer, and is in contact with the free magnetic layer.
Additionally, as the portion of the second insulating layer, for example, a protrusion protruding from the second insulating layer toward the spin-valve thin-film magnetic element may be mentioned.
In such a thin-film magnetic head, since the pair of conductive layers is located on one side in the thickness direction of the free magnetic layer and the pair of bias layers is located on the other side in the thickness direction of the free magnetic layer, the sensing current applied from the conductive layer to the free magnetic layer does not pass through the bias layer having a high resistivity, and the rise in the temperature of the spin-valve thin-film magnetic element is suppressed, and thus the magnetization of the free magnetic layer does not become disordered.
Also, the reading output of the thin-film magnetic head is not decreased.
Furthermore, since the pair of bias layers is disposed on both sides in the track width direction of at least a portion of the second insulating layer, it is possible to narrow the gap in the thin-film magnetic head.
Additionally, although the pinned magnetic layer may have a single-layer structure, the pinned magnetic layer may have a structure in which the pinned magnetic layer is divided into two layers by a nonmagnetic layer composed of a nonmagnetic material and the resulting two layers are magnetically coupled to produce a ferrimagnetic state.
Additionally, although the free magnetic layer may have a single-layer structure, the free magnetic layer may have a structure in which the free magnetic layer is divided into two layers by a nonmagnetic intermediate layer composed of a nonmagnetic material and the resulting two layers are magnetically coupled to produce a ferrimagnetic state.
Furthermore, a diffusion-inhibiting layer for inhibiting diffusion between the free magnetic layer and the nonmagnetic conductive layer may be provided on the free magnetic layer in the portion in contact with the nonmagnetic conductive layer.
In the thin-film magnetic head of the present invention, preferably, the pair of bias layers is disposed on both sides in the track width direction of the second insulating layer, the pair of bias layers is composed of an antiferromagnetic insulating material, and the second shielding layer is in contact with the pair of bias layers and the second insulating layer.
In such a thin-film magnetic head, since the pair of bias layers composed of the antiferromagnetic insulating material is located on both sides in the track width direction of the second insulating layer, it is possible to narrow the gap of the thin-film magnetic head.
Also, since the second shielding layer is in contact with the bias layers composed of the insulating material and the second insulating layer, it is possible to insulate the second shielding layer and the spin-valve thin-film magnetic element from each other.
In the thin-film magnetic head of the present invention, preferably, the second insulating layer is provided with an insulating protrusion protruding toward the spin-valve magnetic element, the pair of bias layers is disposed on both sides in the track width direction of the insulating protrusion, and the pair of bias layers is composed of an antiferromagnetic insulating material or an antiferromagnetic conductive material.
In such a thin-film magnetic head, since the pair of bias layers is disposed on both sides in the track width direction of the insulating protrusion of the second insulating layer, the bias layers are partially or entirely embedded in the second insulating layer.
Since the bias layers are composed of the antiferromagnetic conductive material, which can provide a strong exchange coupling magnetic field, it is possible to reduce the thickness of the bias layers.
Accordingly, it is possible to reduce the thickness of the thin-film magnetic head itself, thus enabling narrowing of the gap.
In the thin-film magnetic head of the present invention, preferably, the second shielding layer is provided with a shielding protrusion protruding toward the spin-valve thin-film magnetic element, the second insulating layer is disposed between the shielding protrusion and the spin-valve thin-film magnetic element, the pair of bias layers is disposed on both sides in the track width direction of the shielding protrusion and the second insulating layer, and the bias layers are composed of an antiferromagnetic insulating material.
In such a thin-film magnetic head, since the pair of bias layers is disposed on both sides in the track width direction of the second insulating layer and the shielding protrusion of the second shielding layer, the bias layers are partially or entirely embedded in the second insulating layer and the second shielding layer. Consequently, it is possible to reduce the thickness of the thin-film magnetic head itself, thus enabling narrowing of the gap.
Also, since the insulating bias layers and the second insulating layer are disposed between the second shielding layer and the spin-valve thin-film magnetic element, it is possible to insulate the second shielding layer and the spin-valve thin-film magnetic element from each other.
In the thin-film magnetic head of the present invention, preferably, the second shielding layer is provided with a shielding protrusion protruding toward the spin-valve thin-film magnetic element, the second insulating layer is disposed between the second shielding layer and the spin-valve thin-film magnetic element, the pair of bias layers is disposed on both sides in the track width direction of the shielding protrusion, and the bias layers are composed of an antiferromagnetic insulating material or an antiferromagnetic conductive material.
In such a thin-film magnetic head, since the pair of bias layers is disposed on both sides in the track width direction of the shielding protrusion of the second shielding layer, the bias layers are partially or entirely embedded in the second shielding layer. Consequently, it is possible to reduce the thickness of the thin-film magnetic head itself, thus enabling narrowing of the gap.
Since the bias layers are composed of the antiferromagnetic conductive material, which can provide a strong exchange coupling magnetic field, it is possible to reduce the thickness of the bias layers, and the thin-film magnetic head itself can be reduced in thickness, thus enabling narrowing of the gap.
In the thin-film magnetic head in which the nonmagnetic conductive layer, etc., are deposited on each side in the thickness direction of the free magnetic layer, preferably, the pair of bias layers is located on both sides in the track width direction of the second nonmagnetic conductive layer, the second pinned magnetic layer, and the second antiferromagnetic layer, and the pair of bias layers is in contact with the free magnetic layer.
In such a thin-film magnetic head, since the bias layers are located on both sides in the track width direction of the second nonmagnetic conductive layer, the second pinned magnetic layer, and the second antiferromagnetic layer, it is possible to reduce the thickness of the spin-valve thin-film magnetic element itself, thus enabling narrowing of the gap in the thin-film magnetic head.
In the thin-film magnetic head in which the nonmagnetic conductive layer, etc., are deposited on one side in the thickness direction of the free magnetic layer, preferably, the pair of conductive layers is located on both sides in the track width direction of the nonmagnetic conductive layer, the pinned magnetic layer, and the antiferromagnetic layer, and the pair of conductive layers is in contact with the free magnetic layer.
In such a thin-film magnetic head, since the conductive layers are located on both sides in the track width direction of the nonmagnetic conductive layer, the pinned magnetic layer, and the antiferromagnetic layer, it is possible to reduce the thickness of the spin-valve thin-film magnetic element itself, thus enabling narrowing of the gap in the thin-film magnetic head.
Also, since the conductive layers are in contact with the free magnetic layer, it is possible to efficiently apply a sensing current to the free magnetic layer.
In the thin-film magnetic head in which the nonmagnetic conductive layer, etc., are deposited on each side in the thickness direction of the free magnetic layer, preferably, the pair of conductive layers is located on both sides in the track width direction of the first nonmagnetic conductive layer, the first pinned magnetic layer, and the first antiferromagnetic layer, and the pair of conductive layers is in contact with the free magnetic layer.
In such a thin-film magnetic head, since the conductive layers are located on both sides in the track width direction of the first nonmagnetic conductive layer, the first pinned magnetic layer, and the first antiferromagnetic layer, it is possible to reduce the thickness of the spin-valve thin-film magnetic element itself, thus enabling narrowing of the gap in the thin-film magnetic head.
Also, since the conductive layers are in contact with the free magnetic layer, it is possible to efficiently apply a sensing current to the free magnetic layer.
Preferably, the antiferromagnetic insulating material is one of NiO and xcex1-Fe2O3.
Preferably, the antiferromagnetic conductive material is one of an X-Mn alloy and an X-Mn-Xxe2x80x2 alloy, where X is at least one element selected from the group consisting of Pt, Pd, Ru, Ir, Rh, and Os, and where Xxe2x80x2 is at least one element selected from the group consisting of Pd, Cr, Ni, Ne, Ar, Xe, and Kr.
In another aspect, a floating-type magnetic head, in accordance with the present invention, includes a slider and any one of thin-film magnetic heads described above.
In accordance with such a floating-type magnetic head, since the thin-film magnetic head, in which Barkhausen noise is decreased, reading output is increased and the gap can be narrowed, is provided, it is possible to construct a floating-type magnetic head which has high sensitivity to an external magnetic field, has high output and is suitable for higher recording densities.